Nancy Freeman-Mitford (28 November 1904 – 30 June 1973), known as Nancy Mitford, was an English novelist, biographer and journalist. One of the renowned Mitford sisters and one of the "Bright Young People" on the London social scene in the inter-war years, she is best remembered for her novels about upper-class life in England and France and for her sharp and often provocative wit. She also established a reputation for herself as a writer of popular historical biographies.
Mitford enjoyed a privileged childhood as the eldest daughter of the Hon. David Freeman-Mitford, later 2nd Baron Redesdale. Educated privately, she had no training as a writer before publishing her first novel in 1931. This early effort and the three that followed it created little stir; it was her two semi-autobiographical postwar novels, The Pursuit of Love (1945) and Love in a Cold Climate (1949), that established her reputation. Mitford's marriage to Peter Rodd in 1933 proved unsatisfactory to both (they divorced in 1957 after a lengthy separation), and during the Second World War she formed a liaison with a Free French officer, Gaston Palewski. He became the love of her life, although the pair were never a formal couple. After the war Mitford settled in France and lived there until her death, maintaining social contact with her many English friends through letters and regular visits.
During the 1950s Mitford was identified with the concept of "U" (upper) and "non-U" language, whereby social origins and standing were identified by words used in everyday speech. She had intended this as a joke, but many took it seriously, and Mitford was considered an authority on manners and breeding—possibly her most recognised legacy. Her later years were bitter-sweet, the success of her biographical studies of Madame de Pompadour, Voltaire and King Louis XIV contrasting with the ultimate failure of her relationship with Palewski. From the late 1960s her health deteriorated, and she endured several years of painful illness before her death in 1973.